Piriformis syndrome- Causes, Symptoms & Treatment

Piriformis syndrome
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Piriformis syndrome

Piriformis syndrome is a painful conditions caused by contractions in the actual piriformis muscle itself. Piriformis syndrome also knowns as ” pseudo-sciatica” or ” false ” sciatica. Piriformis muscle attaches itself to upper femur and runs back across the pelvics to the outsides edges of the sacrum.

 

Introduction

 In the united states each year,  1.5 million people have lumbar  MRI scans to look for the cause of the buttock and leg pain called “Scaitica”.  More than 1.2 million  of those scans are failed  to find out the cause of spine. 300 thousand of the scans are sufficiently +ve that the patient has lumbar spine surgery. Of the 300000 surgeries, as many as 25% fail to relieve the pain. This is because the diagnosis of a spinal cause for the sciatic was incorrect in many cases.

Piriformis syndrome also causes sciatic. Piriformis syndrome treatment is very much less invasive & severe than the  herniated lumbar disks treatment. However,  many doctors are never consider piriformis syndorme as a possible diagnosis.

 

Epidemiology

  • 5-6% of case of sciatica
  • 2.4 million per year
  • In middle-aged patients ( means age 38 years)
  • The ratio of female to male patients with piriformis syndrome has been reported as 6:1:4

 

Pathophysiology

  • Sciatica symptoms due to an involvement of the piriformis muscles.
  • Often referred to as ” Fat wallet syndrome ” or “wallet sciatica”
  • Entrapment of one or more nerves

-Sciatic

-Pudendal

 

Somatic pain

-Myofascial pain syndrome

 

Neuropathic pain

-Compression or irritation of the sciatic nerve

 

Classification

A. Primary

-Myofascial pain caused by trauma.

 

B. Secondary

-Tumors

-Endometriosis

-Adhesions of T.H.R

-Inflammation

-Malunited fractures.

-Pelvic outlet syndrome

 

 

Possible Causes

  • Tightness or spams of the piriformis
  • Trauma to the piriformis
  • Weak gluetals
  • Sitting on the thick surface for long periods  of time

 

Diagnostic criteria

History

  • C/O – Hip, thigh, below knee is pain radiating to ipsilateral.
  • Exacerbated by activity- adduction and internal rotation.
  • Sitting intolerance.
  • FADIR TEST
  • STRETCHING TEST OF FREIBERG
  • PACE TEST – Lying with painful buttocks up and knee in fixed on table, resisted lifting up of knee in fixed position  elicits pain, rules out pain of O.A, disc.
  • SLRT +VE with relief of pain on ER
  • In few cases when patient did not showed strong clinical signs & was not responding to physiotherapy,  we asked for an MRI.
  • No role of X- rays
  • Neurophysiological test are consistent with peroneal division of sciatic nerve.
  • Nerve conduction shows delayed F&H waves reflex.
  • MRI is diagnostic.

 

Risks factors

  • Higher incidence in females – 6:1 ratio
  • Total hip arthropalsty
  • Excessive pronation
  • Strengthening without stretching
  • Sciatic nerve passing through the piriformis – About 15-30% of the population.

 

Signs and symptoms

Sciatic Entrapment

-Pain, tingling, numberness

  • Posterior thigh, hip, leg and buttocks, – Radiating
  • There will be a tenderness in the area of the sciatic notch.
  • Pudendal Entrapment

-Pain, tingling, numbness (Coccyx, groin)

-May cause bowel and /or bladder incontinence.

 

Diagnosing

  • Beatty maneuvar
  • Freiberg test- pictured
  • Pace test
  • Muscle injections  -usually an anesthetic and cortizone.

 

Prognosis

  • Generally very easy to treat
  • Surgery is very rarely recommended to the patient but is generally very successful.
  • Patient are more susceptible to repetitive piriformis syndrome whose sciatic nerve runs through the piriformis muscle.

 

Clinical manifestations

Three specific conditions may contributes to piriformis syndrome.

1. There is a myofascial referred pain from trigger points  in the PM.

2. Adjacent muscles, nerve & vascular entrapment by the PM at the greater sciatic foramen.

3. Dysfunction of the sacroiliac joint.

 

 

Myofascial pain syndrome

  • Gluteal pain 97.9%
  • Pain in the back, groin, perineum, buttocks, hip, back of the thigh are (81.9%)
  • Foot in the rectum and in the area of the coccyx
  • Low back pain 18.1%
  • There is a swelling in the affected leg & disturbance of sexual function are observed in women 13-100%.
  • Disturbances of potency in men.
  • Intense pain when sit ot sqaut.

 

Physical Examination

  • Trigger point tenderness
  • Piriformis sign
  • Freiberg’s sign
  • Pace’s sign
  • Lasegue’s sign
  • Beatty’s maneuver
  • Hughes test
  • Gluteal atrophy
  • There is a shortening of the limb on the affected side
  • Sacroiliac tenderness

 

Imagining modalities

  • Plain pelvic radiography
  • Scintography
  • Ultrasound
  • CT scan
  • MRI
  • MR neurography

 

Diagnostic injection with local anesthesia and sterioids.

 

Treatment

Non operative

Modalities

  • Massage, ultrasound, ice heat

Gait training

Stretching

  • Piriformis, external rotators, IT band

Strengthening

  • Gluteals, adductors, abductors

NSAID’S

 

Operative

  • Not common
  • Surgical release of the piriformis
  • Generally a posterior approach
  • WBAT post surgery for 2 weeks.

 

Treatment protocols

For first 72 hours

  • Rest
  • NSAIDS
  • Muscle relaxants
  • Ultrasounic massage

 

After 72 hours

  • Stretching
  • DTFM
  • Ultrasonic massage

 

After two weeks

Local injection (3)

1. Local anaesthia

2. Local anaesthia + depo medrol

3. Perisciatic

 

Surgery

Robinson

  • Piriformis muscle release
  • Sciatic nerve neurolysis.
  • External rotators & abductors of hip there is no effect on power.
  • Position – lateral
  • Incision – Posterior approach
  • Steps- After splitting gluteus maximus insertion of piriformis is palpated.
  • With the help of allis forceps, tendon is palpated & divided & grasped & dissected till its exit at sciatic notch.
  • Full weight bearing in 5-10 days.
  • Avoid prolonged sitting for 4-6 weeks

Botox

  • Neurotoxin
  • Clostridium botulinum
  • Inhibits release of acetylcholine
  • Leads to functional denervation of muscles.
  • Effective for 6 months
  • U.S.F.D.A approved since December 2000.

 

Observation

  • Total patients of LBA-  754
  • Patients of PS – 67
  • 11 males and 56 females (1:5)
  • 36 right sided and 31 left sided
  • Number of patients with significant reduction of pain on the Visual Analogue Scale at two weeks -50
  • At 4 weeks- 64
  • 17 patient were subjected to injections
  • Of the remaining 4 two lost to F/Up

 

Conclusion

  • Piriformis syndrome is underdiagnosed and undertreated entity.
  • It is very easy to diagnose with few physical signs.
  • When in doubt ask for an MRI
  • The radiologist should be asked to look for any piriformis syndorme while doing screening the spine.
  • With this many causes can be saved from undergoing surgery.

Take home message

  • Piriformis syndrome should be considered as an important differential diagnosis in backache patients.

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